caa a22 4500 388110503 CHVBK 20180307125352.0 cr unu---uuuuu 161130s1999 xx s 000 0 eng 10.1017/S0263593300002583 doi S0263593300002583 pii (NATIONALLICENCE)cambridge-10.1017/S0263593300002583 Grenvillian magmatism of western and central Nordaustlandet, northeastern Svalbard [Elektronische Daten] The basement of the island of Nordaustlandet, northeastern Svalbard, consists of a complex of metasedimentary and metavolcanic rocks, granites and augen gneisses, unconformably overlain by the Neoproterozoic Murchisonfjorden Supergroup. Earlier U-Pb dating of the Laponiafjellet and Kontaktberget granites has shown them to be late Grenvillian, with ages of c. 960 Ma and 940 Ma, respectively. Here, we present conventional U-Pb zircon and monazite data, single zircon Pb-evaporation data and ion microprobe data from the Kapp Hansteen Group and Svartrabbane Formation volcanic and subvolcanic rocks, and from the Fonndalen and Ringåsvatnet augen gneisses of central Nordaustlandet. The combined evidence suggests late Grenvillian magmatic ages of 940-970 Ma for all these rocks, with inherited zircons ranging in age from c. 1200 Ma to 2600 Ma. The investigated rocks vary in chemical composition from andesites to rhyolites and granites, and show generally similar trace and rare earth element patterns, with trace element compositions suggesting a volcanic arc or syn-collisional tectonic setting, and major element compositions suggesting a large sedimentary input to the magmas. Contributions from older crustal material are also supported by Nd isotope data and the presence of inherited zircons. The Grenvillian magmatic rocks thus originated in a series of magmatic events along a continental margin over a time span not longer than 30 Ma. The volcanic rocks were extruded onto folded strata of the Brennevinsfjorden Group-Helvetesflya Formation, which must have been deposited in the time interval 1200-960 Ma. Folding of the metasediments preceded the volcanism, but was synchronous with intrusion of the augen gneiss protolith, and was followed by crustal stabilisation, uplift and erosion. This newly formed Grenvillian crust then served as basement for the deposition of the Neoproterozoic Murchisonfjorden Supergroup. The present outcrop pattern of the Grenvillian rocks is largely the result of large-scale Caledonian folding and doming. Copyright © Royal Society of Edinburgh 1999 augen gneisses nationallicence Caledonides nationallicence geochemistry nationallicence granites nationallicence Grenville nationallicence ion microprobe nationallicence Kober method nationallicence monazite nationallicence Pb-evaporation dating nationallicence Sm-Nd nationallicence U-Pb nationallicence volcanites nationallicence zircon nationallicence Johansson Åke Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden; e-mail: ake.johansson@nrm.se. Larionov Alexander N. Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden; e-mail: alex.larionov@nrm.se. Tebenkov Alexander M. Polar Marine Geological Research Expedition, Pobeda Street 24, 189 510 Lomonosov, Russia; e-mail: tebenkov@neva.spb.ru. Gee David G. Department of Geophysics, Uppsala University, Villävagen 16, S-752 36 Uppsala, Sweden; e-mail: gee@geofys.uu.se. Whitehouse Martin J. Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden; e-mail: martin.whitehouse@nrm.se. Vestin Jessica Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 90/3(1999), 221-254 0263-5933 90:3<221 1999 90 TRE https://doi.org/10.1017/S0263593300002583 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0263593300002583 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Johansson Åke Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden; e-mail: ake.johansson@nrm.se NATIONALLICENCE 700 1- Larionov Alexander N. Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden; e-mail: alex.larionov@nrm.se NATIONALLICENCE 700 1- Tebenkov Alexander M. Polar Marine Geological Research Expedition, Pobeda Street 24, 189 510 Lomonosov, Russia; e-mail: tebenkov@neva.spb.ru NATIONALLICENCE 700 1- Gee David G. Department of Geophysics, Uppsala University, Villävagen 16, S-752 36 Uppsala, Sweden; e-mail: gee@geofys.uu.se NATIONALLICENCE 700 1- Whitehouse Martin J. Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden; e-mail: martin.whitehouse@nrm.se NATIONALLICENCE 700 1- Vestin Jessica Laboratory for Isotope Geology, Swedish Museum of Natural History, Box 50 007, S-104 05 Stockholm, Sweden NATIONALLICENCE 773 0- Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 90/3(1999), 221-254 0263-5933 90:3<221 1999 90 TRE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge